Car roof racks

Is there a surfboard rack that you can lock the surfboard on with a key instead of just straps. I'm worried that someone may steal my board whenever I leave it unattended, like when I go eat lunch after surfing. I have to be constantly watching the board. A surfboard rack that can keep my board secure and safe would be cool because I can leave it unattended without worries. I think I've seen one in a magazine but don't know the name or where to get it. Anybody know what I'm talking about?